ABSTRACT For over a decade, research funded by the parent grant (R01AG026291) has made substantial contributions to our understanding of the influences of the workplace environment and other exposures accrued during work-life on health and economic trajectories in an aging population. These new findings have been possible because of the unique access to a wide variety of data sources from a single firm with plants located across the United States. Despite the impact of these findings for workplace changes that promote healthy aging and longevity, the cohort has not yet been utilized for examining racial/ethnic or rural/urban health disparities. The AMC is a study population of more than 142,000 employees at 675 facilities widely geographically distributed across the United States. Although 72% are white, there are almost 20,000 blacks and more than 10,000 Latinxs in the cohort - far greater numbers than are available in any other ongoing cohort study of an aging workforce. We will achieve three aims in this supplemental application, all of which are intended to demonstrate the utility of this cohort for answering critical questions to address racial and geographically-related health disparities. First, we will test for potential racial and ethnic bias inherent in the health risk score, a score derived by the health insurer to predict health care costs. Second, we will investigate the potential influence of factors related to place of residence on health disparities for rural workers. Finally, we will examine the extent to which job-level and work schedule-related factors contribute to racial and geographic disparities using a mediation analysis framework. This supplemental research project will allow us to extend a longstanding research program to leverage existing administrative data and new data sources to adopt a serious focus on racial/ethnic and rural/urban health disparities in the AMC population, which in turn may offer broad insights to disparities that occur throughout work life and contribute to later health and economic outcomes.